The present invention relates to communications equipment, and more particularly to a device for use with facsimile machines and/or computers to allow protected transmission and receipt of confidential messages.
The problem of ensuring confidentiality of facsimile transmissions has long been recognized in the communications industry. It is well known that facsimile transmissions can be received by non-designated addressee, and that confidentiality of the transmission can be easily compromised. To overcome this problem, various devices have been proposed for encoding an outgoing message, so that only a designated facsimile machine equipped with the key for decoding the message can decrypt the message into a readable form. Some of these devices can be found in, for example, U.S. Patent Nos.:
U.S. PATENT NO. ISSUE DATE 3,715,478 February 6, 1973 4,091,423 May 23, 1978 4,989,244 January 29, 1991 5,241,595 August 31, 1993 5,321,749 June 14, 1994 5,351,136 September 27, 1994
Additionally, a number of devices have been patented for encoding textual data with the use of a computer. Some of these devices are disclosed in U.S. Patent Nos.
 U.S. PATENT NO. ISSUE DATE 5,159,635 October 27, 1992 5,245,655 September 14, 1993
Standard facsimile machines use optical scanners for reading the message to be transmitted, with the image then being changed into a binary code, and then encoded into a dual tone modulated frequency (DTMF) signal suitable for facsimile transmission. The receiving facsimile machine converts the DTMF signal into a binary code, which is then decoded to receive the textual or graphic image transmitted by the first facsimile machine.
Many of the known devices utilize decoding electronic means which are built into the facsimile machine and which can be activated by the user with the use of a keyboard or a computer.
Some of these devices also have means for storing the encoded information which can be retrieved by a user who possesses the password or a decoder.
However, none of the known devices discloses a portable device which can be easily connected to a standard facsimile machine to receive the intended message and to store the information until the user is ready to read it through a facsimile machine or a computer.